It's a romantic expression that conveys the speaker's feelings for the person they are addressing. They are expressing their desire to wait for the other person, because they have feelings for them.
Here's a breakdown of the meaning:
* Deng ni (等你): Wait for you
* Yin wei (因为): Because
* Wo xi huan (我喜欢): I like you
It's a very direct and heartfelt expression of affection.